In this dissertation I explore the application of two novel modeling techniques for improving risk analysis of vector-borne disease and discuss their potential use in integrating environmental risk assessment that guides environmental and public health decisions. Techniques for analyzing risk have been considered inadequate due to a lack of understanding of the problem and an appropriate analytic-deliberative process clarifying the meaning of analytic findings and uncertainty (National Research Council (NRC), 1996; Peterman and Anderson, 1999). Thus, new integrative risk analysis tools are needed that are responsive to more complex environmental problems. In this work, I develop a qualitative community model that combines a conventional biomathematical model of vector-borne disease transmission with recent developments in community modeling. My procedure predicts the change in risk of vector-borne disease from press perturbations, a disturbance that results in a permanent change in a growth parameter. I also use a Relational Bayesian Modeling technique to exploit existing data to determine plausible mechanisms and geospatial and temporal patterns of disease spread. I apply these tools to Lyme disease and West Nile Encephalitis as examples of two different vector-borne diseases associated with complex ecological communities. Both the qualitative modeling and Bayesian methods provide an integrated risk analysis framework that identifies relationships important in the system and thus, guide the application of quantitative models or provide sufficient information for management decisions. / Graduation date: 2003

No description available.

Uninfected larvae of Ixodes dammini, lxodes cookei, and Amblyomma americanum were fed on hamsters that had been injected intraperitoneally with a 0.5.ml sample of Borrelia burgdorferl (2.5 X 107 spirochetes per ml) 21 days earlier. A total of 108 of these larvae comprised of 36 1. dammini, 36 i. cookei, and 36 A. americanum were aseptically dissected and examined by darkfield and immunofluorescent microscopy for the presence of B. burgdorferl within 48 hours of feeding on the B. burgdorferi infected hamsters. The removal and examination of the midgut diverticula revealed that 32/36 (88.9%) of the l. dammini larvae contained B. burgdorferl. Only 5/36 (13.9%) of the l. cookei larvae and 7/36 of the A. americanum larvae harbored spirochetes in their midgut diverticula.A portion of the nymphs that molted from the above larvae were also dissected and examined by darkfleld and indirect immunofluorescent techniques. Borrelia burgdorferi were observed in the midgut diverticula of 94/107 (87.8%) of the l. dammini nymphs. None of the 30 (0%) l. cookei nymphs examined were found positive for spirochetes and only 1/60 (1.7%) of the A. americanum nymphs was found positive for B. burgdorrerl.A total of 83 lL dammini, 53 A. americanum, and 161. cookei nymphs reared from larvae that fed to repletion on hamsters infected with B. burgdorrerl were allowed to feed on uninfected hamsters to assess transmission of B. burgdorrerl. Transmission was demonstrated only by the l. dammlnl nymphs. The findings of this study suggest that it is extremely unlikely that l. cookei can serve as a vector for B. burgdorrerl, but do not rule out completely the possibility that A. americanum may be able to maintain B, burgdorrerl infections transstadially and, under certain conditions, transmit the organisms to vertebrate hosts. / Department of Physiology and Health Science

Uninfected nymphs of Ixodes scapularis and Amblyomma americanum were fed on hamsters that had been injected intraperitoneally with a 0.5 ml sample of Borrelia burgdorferi (2.5 X 10' spirochetes per ml) 30 days earlier. All nymphs fed to repletion and were then housed during the molting process. In order to assess their ability to transmit the spirochetes, the resulting l. scapularis and A. americanum adults were allowed to feed on uninfected rabbits.Dissection of the adult l. scapularis ticks revealed 9/12 (75%) to harbor motile spirochetes, identified as B. burgdorferi by darkfield microscopy, isolation in BSK II medium, and indirect immunofluorescent antibody staining with the monoclonal antibody H5332. Transmission was successful to one of two New Zealand White rabbits by these infected ticks.Dissection of the adult A. americanum ticks revealed 0/150 (0%) to harbor spirochetes. Transmission to each of three rabbits was unsuccessful. However, 5/90 (5.6%) cultures of midgut material from these same ticks, harbored non-motile spirochete-like bodies. The identity of these "spirochetes" is unknown. / Department of Biology

Thesis (Ph. D.)--Ohio State University, 2008.

Thesis (Ph.D.)--University of Delaware, 2008. / Principal faculty advisors: Jack B. Gingrich and Douglas W. Tallamy, Dept. of Entomology & Wildlife Ecology. Includes bibliographical references.

Three studies relating to the vector competency of several species of ticks and <i>Simulium</i> spp. (blackflies) for <i>Ehrlichia risticii</i>, causative agent of Potomac horse fever (PHF) and <i>Amblyomma variegatum</i> for <i>Cowdria ruminantium</i>, causative agent of heartwater, are described. <i>Dermacentor variabilis, Rhipicephalus sanguineus, Amblyomma americanum and Ixodes scapularis</i> ticks were investigated for their ability to acquire and transmit PHF. Larval and nymphal ticks were exposed to <i>E. risticii</i> by feeding on mice inoculated with the organism. Molted exposed ticks were then allowed to feed on susceptible ponies or mice and were examined by light and electron microscopy. No evidence of transmission, either clinically or by seroconversion in mice or ponies was observed. Blackflies (<i>Simulium</i> spp.) were trapped in an area endemic for PHF and inoculated into mice in an attempt to demonstrate <i>I. risticii</i>. No evidence of seroconversion by mice to <i>E. risticii</i> was observed. Two laboratory colonies of <i>Amblyomma variegatum</i> ticks were investigated for their ability to acquire and transmit C. <i>ruminantium</i> and was febrile. Nymphs from both laboratory groups were simultaneously fed on a goat that had been infected with C. <i>ruminantium</i> and was febrile. Engorged nymphs from both groups were replete from feeding on three consecutive days. Nymphs from both groups were then incubated under identical conditions until molting. / Ph. D.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 65-76.

No description available.

Title from title page of PDF (University of Missouri--St. Louis, viewed March 9, 2010). Includes bibliographical references.